Tuesday 16th January 17:00 UTC

Main Agenda

  • reminder of only 5 weeks until march 1st deadline for completion of cavatools and cryptoprimitives.

Discussion of commit frequency and other points mentioned in this email thread. Points to be discussed:

After meeting discussion, points agreed upon will be documented in the wiki.


  • will need volunteers for the devroom:
    • Watch speaker, keep track of time
    • Carry mic to audience, keep questions short
    • Watch the door, make sure talk doesn't get disturbed (people come in in the middle of a talk)
  • Make sure PDF slides for the talks are:
    • Uploaded to pretalx platform in good time (two weeks before FOSDEM?)
    • Resolution set to 1280x800 resolution, preferably 800x600.
    • Higher-res slides can be uploaded later, but for the actual slides to be used during the event, resolution must be as mentioned above.
    • Put all PDFs on the laptop to be used for presentations. Make sure we have copies just in case.
    • More info on slides from Luke: email archive

Meeting notes:


  • bug #980
    • Still some work required. A few days until
    • Two types of pseudocode: instructions, python functions
    • For now provides prototypes for many features


Jacob provided great help:

maddedu would be useful if you have a packed 130 bit number
in words where the non-msb words have 64-bits per word, the
code you had last i checked instead has 44-bits per register used

this is the pattern used by the x + y remap mode...which
isn't working yet, so svindex is suitable for now

maddedu also has carry-out, which you don't have here 
so maddld is sufficient 
or the x + y remap once that's implemented 
setup shapes with svindex insn 
no, those are offset by the register specified in the sv. insn
that remap is applied to

svindex has element numbers, not x,y,z 
x,y,z are used for other remap modes 
yes, use the svindex insn 
you specify the vector to load element numbers from in the svindex insn
but they're accessed with element-sized chunks with element size
determined by svindex

svindex is if you want only one sv.maddld insn that loops 9 times 
lemme move to my desktop so i can type easier... 
ok, so you'll want a mod-3 matrix remap in one SVSHAPE register,
and svindex remap in another SVSHAPE register

so run svshape to set the matrix remap, then run svindex
to overwrite one remap...

svshape writes all 4 SVSHAPE registers, svindex can set the SVSHAPE
register you specify

(or all 4, but you don't want that mode) 
so test_1_sv_index is an example of what you want... 
it sets SVSHAPE2 
encoded in the LSB 2 bits of the operand that's 14 
the rmm operand 
see comments immediately above 
see line 396 of simplev.mdwn for how rmm is used 
in openpower-isa.git 
* **SVG** - GPR SVG<<2 to be used for Indexing 
so if you want the indexes to be in r4,r5,r6... set SVG to 1 which
comes out to r4 (1 << 2)

yes, a value of zero means use element 0 
so, if you want remap to use elements 1,2,3,4,5,6,7,8 set the first
register to 0x0807060504030201 and use byte elwid 
the svindex elwid, not the sv.insn elwid, they're independent 
svremap tells the following sv.insn which SVSHAPE[0-3]
register to use for each operand

you don't want to set the SVSHAPE register directly, instead put the
indexes in GPRs and svindex insn sets SVSHAPE to point to those GPRs

ok, so if your indexes are in r4,r5 with byte elements, afaict you
want svindex 1, 1, 9, 3, 0, 1, 0 which sets byte mode, sets SVSHAPE1 


  • Recovering from a cold (worst of it already happened on the weekend, now mostly blocked nose).
  • Bug #1048, Luke and Jacob made comments regarding the summary, I'll work on it when available.
  • Checked that RfP for Red was paid, so added extra commentary on IRC (continued from walkthrough Luke and I did last month).
  • Created a discussion page for the "git commit frequency" topic that came up last week: sync up 2024-01-16 discussion. Announcement on IRC
  • TODO:
    • Change my main email from technepisteme.xyz to the gmail one.
    • Redo the calendar invites for the sync-up meetings.


  • suggested that presentations should be submitted much closer to fosdem (few days), since 2 weeks is too early. I will not be ready by 2 weeks before.
  • (didn't actually get around to during meeting:) not a whole lot, will start working on presentation, helped resolve issue with luke & dmitry, fixed some bugs for dmitry.